Blood pressure measuring device

ABSTRACT

The blood pressure measuring device (10) has a bowl-shaped casing (11) in which is arranged a pressure measuring system with a measuring scale (13) and indicator. The casing (11) is closed at its upper edge by a transparent cover plate (25). This primary casing (11) is surrounded at a given distance on the outside by a protective housing (15), whereby the base (18) of the protective housing (15) is combined in one piece with the base (16) of the primary casing (11). The compressed air line is connected either through a hole (22) in the base (16) of the casing (11) or through the casing walls. In the latter case, there is a material bridge in the space between the wall of the primary casing (11) and of the protective housing (15).

BACKGROUND OF THE INVENTION

In most of the known sphygmomanometers the manometer is contained in ausually cup-shaped case and is mounted therein on one of the parts ofthe case. This case also contains the dial through which the meter shaftpasses. Above the dial the pointer is mounted on the meter shaft. Thedial, and the pointer are covered by a crystal which is either inserteddirectly on the upper margin of the case or is inserted in a separatebezel which in turn is joined to the margin of the case (EP-A-0 008 351A2). In both cases the disk seals the interior of the case, with theparts contained therein, from the exterior.

If such a sphygmomanometer falls onto a hard surface there is the dangerthat the case may be damaged, especially that it may be distorted. Inthe area of the bottom, and of the transition from the bottom to thecircumferential wall, the case has of its nature a comparatively greatstability of shape, so that in this area the distortions caused bydropping generally remain comparatively slight. It is different when thecase strikes in the area of its top margin where the dial and thecrystal become damaged. The dial may be bent or may bulge. Suchdeformation of the dial can be so great that the pointer can no longermove across the dial.

If the case becomes deformed the dial may also snap out of its mounting.The same applies to the crystal. In the event of a particularly hardshock the spiral return spring of the manometer mechanism may becomedamaged, when for example one or more of its coils loop over one anotherand become entangled. In the case of all such damage or even destructionof individual parts, the entire sphygmomanometer becomes useless.

SUMMARY OF THE INVENTION

It is the object of the invention to construct a sphygmomanometer suchthat the damage or destruction caused by dropping it will at least bereduced if not entirely prevented.

Since the primary case is surrounded by a protective case, if thesphygmomanometer falls on a hard surface the circumferential wall of theinterior primary case might not be struck, so it cannot be deformed.Consequently the danger that the meter and its parts contained in theprimary case might be damaged is almost entirely avoided. In particular,the primary case is prevented from being dented in the area of its uppermargin where the dial and crystal are fastened. Therefore these partsare virtually entirely protected against damage. Since the bottom of theprotective case is integral, at least at approximately the same level,with the outside of the bottom of the circumferential wall of theprimary case, the strength of the entire case is considerably increasedin this area. For this reason alone, deformation of the primary case inthis area is entirely prevented, and the danger of deformation even ofthe protective case is greatly diminished.

If the sphygmomanometer is designed in accordance with claim 2, itbecomes easier to attach the manometer mechanism to the other parts ofthe sphygmomanometer which are disposed on the outside of the bottom ofthe case. In an alternative configuration of the sphygmomanometeraccording to claim 3, the same will be true for attachment in the areaof the side wall of the entire case, if the rest of the parts of thesphygmomanometer are attached there.

In an embodiment of the sphygmomanometer according to claim 4, the guardring disposed on the upper margin of the protective case closes off thegap between the circumferential wall of the primary case and thecircumferential wall of the protective case. This at least greatlyreduces, if not entirely prevents, the penetration of dust and dirt intothis gap. Also, since the guard ring extends inward at least to the edgeof the primary case or extends slightly past it, the upper edge of theprimary case with the crystal placed in it and the dial set below it arealso protected at the face of the sphygmomanometer.

In a further development of the sphygmomanometer according to claim 5,the danger of damage to the guard ring is reduced since its beveledoutside face eliminates the sharp edge which would be more exposed todamage by striking against a hard surface. This shaping of the guardring increases the impact area and thereby reduces the stress per unitarea at the point of impact. Furthermore, it makes it easier for thecase to roll on the surface, which also contributes to the reduction ofpeak stresses.

By a configuration of the sphygmomanometer according to claim 6, theassembly of the guard ring is simplified and facilitated.

In an embodiment of the sphygmomanometer according to claim 7, theelastic ring between the guard ring and the protective case absorbs partof the impact energy if the case should strike with its guard ringagainst a hard surface. In this manner too, the danger of damage to theparts of the sphygmomanometer is considerably reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained with the aid of two embodimentsrepresented in the drawing, wherein:

FIG. 1 is a partially cut-away view of a case of the sphygmomanometer inwhich most of the parts of the manometer mechanism are not represented,

FIG. 2 is a partially cut-away view of the case of a second embodimentof the sphygmomanometer, and

FIG. 3 is a view of the case according to FIG. 2 represented as rotated90° on its axis.

The sphygmomanometer 10 seen in section in FIG. 1 has an at leastapproximately cup-shaped case 11. In its interior 12 the manometermechanism of conventional design is housed, of which only the dial 13 isrepresented in FIG. 1.

The case 11 is a kind of double case with an interior or primary case,referred to hereinafter as primary case 14, and with an external orsecondary case which, due to its special function, will be referred tohereinafter as protective case 15. The case 11 with its two parts 14 and15 is made in one piece of molded plastic.

The primary case 14 is cup-shaped and has a bottom 16 and acircumferential wall 17. The protective case 15 has at leastapproximately the same shape and also has a bottom 18 and acircumferential wall 19. The bottom 18 of the protective case 15 joinsat the same level the bottom 16 of the primary case, at the outside ofthe circumferential wall 17 thereof. Thus the bottom 18 is reduced to anannular area whose radial width is only as great as the radial width ofthe gap 21 between the circumferential wall 17 of the primary case andthe circumferential wall 19 of the protective case 15.

The primary case 14 has in the center of the circle of its bottom 16 acylindrical bore 22 through which the compressed air carrying parts ofthe sphygmomanometer 10 communicate with the manometer mechanismcontained in the interior chamber 12.

At the upper margin of the wall 17 of the primary case 14, two ledges 23and 24 of graded diameter are present. On the lower inner ledge 23 liesthe margin of the dial 13, and the margin of a crystal 25 lies on theupper ledge. The circumferential surface of the crystal 25 and thesection of the inside of the circumferential wall 17 adjoining the ledge24 are configured as frustoconical surfaces with a very small coneangle. This results in a kind of snap fastening which holds the crystal25 on the top margin of the primary case 14 when it has been insertedtherein. The crystal 25 then also holds the dial 13 in place.

On the circumferential wall 19 of the protective case, a rabbet 26 witha flat, circular surface is present. It is defined on the inside by acylindrical surface 27. In the adjoining longitudinal section of thecircumferential wall 19, whose outside has at least approximately theshape of a cylinder, there is formed an annular bead 28 protrudingradially outward. This bead, as a projection of the wall, forms the onepart of a snap fastening 29 by which a guard ring 31 is held, which isplaced downwardly onto the circumferential wall of the protective case15. On the inside of a circumferential wall 32 of the guard ring 31there is formed an inwardly projecting annular bead 33 which catches onthe annular bead 28 on the circumferential wall 19 and acts as the catchof the snap fastening 29.

The guard ring 31 has a gable-like cross section with sides of unequalwidth. The outer side 34 of the guard ring 31 has a curved profile, andthe inner side 35 of the guard ring 31 has a straight profile.

As it can be seen in FIG. 1, the guard ring 31 reaches inwardly from theoutside of the circumferential wall 19 of the protective case 15 tobeyond the circumferential wall 17 of the primary case 14, so that itslightly overlaps the crystal 25 at the margin of the wall 17. Themargin of the guard ring 31 is not directly in contact with the crystal25 but is at a short distance away from it for safety, so that if theguard ring 31 undergoes an elastic deformation it will not immediatelyimpact the crystal 25.

To enable the guard ring 31 to serve its purpose in an optimum manner,it is best made of a plastic having greater resistance to impact andfracture than the material of the case 11.

The snap fastening 29 is so configured that it can still shift slightlyin the axial direction against the protective case 15 when it is snappedonto the margin of the latter. Between the rabbet 26 of the protectivecase 15 and the downwardly directed face of the circumferential wall 32of the guard ring, an intermediate ring 36 which is resilient at leastin the axial direction is inserted. This ring damps shocks which undercertain circumstances strike downwardly against the guard ring 31.

Instead of an intermediate ring 16 made of an elastomer, a ring made ofa less elastic or even hard material can be used, which on account ofits material--a metal for example--or due to its special color providesa contrast with the color of the protective case 15 and/or with theguard ring 31.

In the sphygmomanometer shown partially in section in FIGS. 2 and 3,only the case 41 is different in some ways from case 11. The other partsof the sphygmomanometer 40, which are not all shown, are to beconsidered as the same or at least similar to the corresponding parts ofsphygmomanometer 10.

The outside and inside dimensions of case 41 are virtually the same asthose of case 11. It likewise has two parts, namely the primary case 42and the protective case 43.

The manometer mechanism contained in the interior of case 41 is notconnected by a bore in the bottom of the case to the other parts of thesphygmomanometer 40 which carry compressed air, but is connected by aconnecting line 44 which is disposed in the area of the circumferentialwall 45 of the primary case 42 and the circumferential wall 46 of theprotective case 43. This connecting line 44 is formed by a through-bore47 in the circumferential wall 45, by a through-bore 48 in thecircumferential wall 46, and by a through-bore 49 in a bridge 51. In thearea of the connecting line 47, this bridge 51 fills up the gap 52running all the way around between the circumferential wall 45 of theprimary case 42 and the circumferential wall 46 of the protective case43, and thus seals off the connecting line 44.

I claim:
 1. A sphygmomanometer comprising:a primary case having a bottomwall and a circumferential wall extending from said bottom wall todefine an interior space therebetween; a manometer having a shaft andbeing fastened to said primary case within said interior space; a dialdisposed on an upper margin of the primary case, said shaft passingthrough said dial; a pointer fixed to said shaft above a surface of saiddial; a crystal removably joined to said upper margin; a protective casehaving a bottom wall and a circumferential wall, said circumferentialwall of said protective case extending from said bottom wall of saidprotective case and surrounding said circumferential wall of saidprimary case to define a gap therebetween, said bottom wall of saidprotective case integrally joined to an outside surface of saidcircumferential wall of said primary case at approximately a same levelas said bottom wall of said primary case such that said primary and aprotective cases are a single piece construction.
 2. A sphygmomanometeras recited in claim 1, further comprising a cuff and a compressed airline connecting said cuff to said manometer, and wherein said bottomwall of said primary case has a through-bore therein through which saidcompressed air line passes.
 3. A sphygmomanometer as recited in claim 1,further comprising a bridge disposed in said gap, a cuff and acompressed air line connecting said cuff to said manometer, and whereinsaid circumferential walls of said primary and protective casesrespectively include first and second through-bores which are alignedwith each other, said compressed air line passes through said first andsecond through-bores, and said bridge seals and encompasses a section ofsaid gap which is located between said first and second through-bores.4. A sphygmomanometer as recited in claim 1, further comprising a guardring disposed at a top margin of said circumferential wall of saidprotective case, said guard ring extending from an outside surface ofsaid circumferential wall of said protective case to at least said uppermargin of said primary case but not beyond a scale portion of said dial,and said guard ring being made from a material which has a greaterimpact and fracture resistance than a material from which the protectivecase is made.
 5. A sphygmomanometer as recited in claim 4, wherein anoutside surface of said guard ring is tapered away from said top marginand is configured as at least one of a truncated cone mantle surface anda surface of a section of a sphere.
 6. A sphygmomanometer as recited inclaim 4, further comprising a snap fastener, said snap fastenerincluding a partially circumferential projection and a partiallycircumferential indentation into which said circumferential projectionis removably disposed to secure said guard ring to said protective case.7. A sphygmomanometer as recited in claim 6, further comprising anintermediate ring which is elastically flexible at least in an axialdirection of said shaft, said intermediate ring disposed between anannular surface of said guard ring and an annular surface of saidprotective case such that said snap fastener is flexible in said axialdirection or moveable in the axial direction.